A Coast Guard boat patrols in Boston Harbor on March 10. (Michael Dwyer/AP)

Dozens of lawmakers are urging House leaders who oversee the budget to block any move by the Trump administration to slash Coast Guard funding, saying a proposal to do so is “cause for serious alarm” and “nonsensical” if the president plans to expand the other armed services.

The bipartisan call was issued Monday in a letter to Rep. John Carter (R.-Tex.), who leads the House Appropriations subcommittee on homeland security, and Rep. Lucille Roybal-Allard (D.-Calif.), the subcommittee’s ranking Democrat. The effort was spearheaded by Rep. Duncan D. Hunter (R.-Calif.), who supported Donald Trump during his campaign but disagrees with an Office of Management and Budget proposal to cut about $500 million for a new Coast Guard national security cutter and millions of dollars for long-standing efforts such as Maritime Security Response Teams, which patrol ports and other sensitive waterways for potential terrorists.

The proposed cuts would combine with others to the Transportation Security Administration and Federal Emergency Management Agency to help pay for President Trump’s multibillion-dollar southern border wall and crackdown on illegal immigration.

Lawmakers argue in the letter that OMB appears to have discounted that while the Coast Guard is not a part of the Defense Department, it is part of the U.S. military and actively involved in efforts to stop illegal immigration and terrorism. Given Trump’s efforts to strengthen border security, it’s likely that the flow of illegal drugs and immigrants offshore will only increase, meriting a “sizable budget increase” to the Coast Guard, the letter said.

“The concern with OMB’s financial outline is that it severely discounts the value and effectiveness of the U.S. Coast Guard in drug interdiction and maritime security, and its standing as an Armed Service,” the lawmakers said. “Further, there appears to be a bias against the Coast Guard by career bureaucrats that threatens to undermine the Coast Guard mission and, whether intended or not, to degrade its ability to effectively conduct its mission.”

The Coast Guard has operated “under the realities of severe budget limitations” for years, the letter said.

“It’s nonsensical to pursue a policy of rebuilding the Armed Forces while proposing large reductions to the U.S. Coast Guard budget,” it added. “Without question, OMB’s proposed budget cut targeting the Coast Guard directly contradicts the President’s stated goals.”

Hunter’s office led the effort to solicit signatures and send the letter, said Joe Kasper, a spokesman for the congressman. There are nearly 60 other signatories, including Republicans and Democrats who served in the military, such as Reps. Martha McSally (R-Ariz.), Adam Kinzinger (R-Ill.), Seth Moulton (D-Mass.) and Peter A. DeFazio (D-Ore.).

The proposed cuts leaked in a draft last week. Michael Short, a White House spokesman, cautioned at the time that the Trump administration was still early in the process of working on the budget, which will be submitted later this month to Congress.